Described below is a pressure measurement device for a rotor blade of a wind energy installation having a hollow body that is closed in a gastight fashion and has at least one pressure deformable diaphragm, a rotor blade of a wind energy installation having at least one pressure measurement device as described below, a wind energy installation having at least one rotor blade as described below, a method for determining a wind force acting on the rotor blade, as well as a use of the method.
Modern wind energy installations have a tower and a gondola, mounted rotatably on the tower, with a rotor. A high efficiency, a minimum sound emission, a low material use and a long service life are the criteria for the design and optimization of such wind energy installations. They are increasingly being produced in ever higher power classes. The aim is to achieve an ever higher efficiency and an increased output power referred to the spatial requirement of the installation. Particularly in the offshore sector, it is necessary to install relatively large wind energy installations because of the expensive provision of foundations. Such wind energy installations presently have rotor diameters of up to 130 m. The ever larger dimensions are attended by various problems in the design and operation of the installation. Firstly, the height gradation of the wind speed becomes noticeable because of the large rotor diameter. In this case, the individual rotor blades assigned to the rotor are partially exposed to strongly differing wind speeds. Consequently, each rotor blade operates with different efficiency in the case of a fixed rotor blade position (pitch). Secondly, a different wind load has a problematic effect on the individual rotor blades.
An excessively high wind load on an individual rotor blade can lead to intense sagging of the rotor blade, and thus to damage to it. Moreover, wind load of different intensity on the various rotor blades leads to a lateral torque on the shaft via which the rotor is connected in a rotatably supported fashion to a gearbox arranged in the tower of the wind energy installation. Such a torque loads the gearbox, and this can frequently lead to premature failure of gearbox parts.
Aneroid barometers can be used to measure air pressures. Such a barometer includes a hollow body, made of thin sheet metal, that resembles a box and is provided with a diaphragm, and in which a vacuum or underpressure prevails. The air pressure deforms the diaphragm. This deformation is transmitted via a mechanical system to a pointer such that the prevailing pressure can be read off from the pointer position.
EP 0 970 308 B1 specifies a wind energy installation having a wind speed measurement system. The wind speed measurement system is designed in this case as a laser anemometry system. Laser light is hereby emitted with the aid of a laser, and particles in the air are irradiated. The laser light is partially backscattered by the irradiated particles and detected by a detector. The speed of the particles can be inferred from analysis of the backscattered laser light. Since the speed of the particles corresponds to the wind speed, the wind speed in front of the wind turbine is determined in this way. Such a measurement is relatively complicated and can be carried out as a rule only by service staff by way of sampling.